Not the Whole Story — Why Mainframe Software is Really the Crown Jewel

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There
have been a number of series of operating systems for IBM’s mainframes –
from the mainline original OS1 and OS2 to OS/MFT to OS/MVT to TSS to
MVS to OS/390 to z/OS. The lineage carries the rights to the crown as
the jewels of IBM’s Mainframe Empire. Almost of all of the black magic
that other platforms’ operating systems hope to deliver under the banner
of “mainframe-like” descend from this lineage. But there are other
family lines in IBM’s royal family that have given us virtual machines
and hypervisor control (VM and z/VM), scaled down functionality with
greater operational simplicity (the original DOS to VSE to z/VSE), to
large-scale transaction processing (TPF - primarily for airline
reservation systems), and to several others developed outside of IBM
(including MTS - Michigan Terminal System - from my college and early
professional days).